High silicon stainless steel alloys and turbocharger kinematic components formed from the same

ABSTRACT

An austenitic stainless steel alloy includes, by weight, about 25% to about 27% chromium, about 20% to about 21% nickel, about 1 to about 2% niobium, about 0.75% to about 1.7% carbon, about 3.5% to about 4.0% silicon, about 2% to about 3% tungsten, about 1.5% to about 2.5% copper, about 2% to about 2.5% molybdenum, and a balance of iron, and other inevitable/unavoidable impurities that are present in trace amounts. Sulfur is excluded from the alloy beyond impurity levels. In one example, a turbocharger kinematic component is made at least in part using this stainless steel alloy.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to and claims all available benefit of U.S.Provisional Patent Application 63/266,632 filed Jan. 11, 2022, theentire contents of which are herein incorporated by reference.

TECHNICAL FIELD

The present disclosure generally relates to iron-based alloys, such asaustenitic stainless steel alloys, and articles of manufacture formedtherefrom. More particularly, the present disclosure relates tostainless steel alloys with a relatively high silicon content used, forexample, in turbine and turbocharger kinematic components.

BACKGROUND

In the context of turbine engines, turbochargers use heat and volumetricflow of engine exhaust gas to pressurize or boost an intake air streaminto a combustion chamber. Specifically, exhaust gas from the engine isrouted into a turbocharger turbine housing. A turbine is mounted insidethe housing, and the exhaust gas flow causes the turbine to spin. Theturbine is mounted on one end of a shaft that has a radial aircompressor mounted on an opposite end thereof. Thus, rotary action ofthe turbine also causes the air compressor to spin. The spinning actionof the air compressor causes intake air to enter a compressor housingand to be pressurized or boosted before the intake air is mixed withfuel and combusted within the engine combustion chamber.

Various systems within turbochargers include tribological interfaces,that is, surfaces of components that interact with and move relative toone another while the turbocharger is in operation. Such components,which are commonly referred to as kinematic components, may besusceptible to friction and wear, especially at elevated temperatures,which reduces their service life. Examples of turbocharger systems thatmay include kinematic components include waste-gate systems, whichdivert exhaust gasses away from the turbine to regulate airflow to theturbine, and variable geometry systems, which include a row of moveableinlet vanes to accomplish the same purpose. These systems commonlyinclude various components such as shafts, bushings, valves, and thelike, which are kinematic components because they interact and moverelative to one another, and they are thus subject to friction wear. Inthe prior art, 310-grade stainless steel may have been used for suchcomponents, but such stainless steel has proven undesirable due to itsrelatively high cost. An effective (and less expensive) substitutetherefore would be welcome in the art, as long as the appropriatematerial properties are retained.

Accordingly, it is desirable to provide materials that are suitable foruse in fabricating kinematic components for turbine engines that canresist wear during elevated temperature operations. Furthermore, otherdesirable features and characteristics of the inventive subject matterwill become apparent from the subsequent detailed description of theinventive subject matter and the appended claims, taken in conjunctionwith the accompanying drawings and this background of the inventivesubject matter.

BRIEF SUMMARY

Austenitic stainless steel alloys, and turbocharger kinematic componentsfabricated from such alloys, are provided.

In an embodiment, by way of example only, an austenitic stainless steelalloy includes or consists of, by weight, about 25% to about 27%chromium, about 20% to about 21% nickel, about 1 to about 2% niobium,about 0.75% to about 1.7% carbon, about 3.5% to about 4.0% silicon,about 2% to about 3% tungsten, about 1.5% to about 2.5% copper, about 2%to about 2.5% molybdenum, and a balance of iron, and otherinevitable/unavoidable impurities that are present in trace amounts.Sulfur is excluded from the alloy beyond impurity levels.

With regard to the foregoing alloy embodiments: the amount of chromiummay be limited to about 25.5% to about 26.5%; alternatively oradditionally, the amount of nickel may be limited to about 20.25% toabout 20.75%; alternatively or additionally, the amount of niobium maybe limited to about 1.25% to about 1.75%; alternatively or additionally,the amount of carbon may be limited to about 1.3% to about 1.7%;alternatively or additionally, the amount of silicon may be limited toabout 3.6% to about 4.0%; alternatively or additionally, the amount oftungsten may be limited to about 2.25% to about 2.75%; alternatively oradditionally, the amount of copper may be limited to about 1.75% toabout 2.25%; and, alternatively or additionally, the amount ofmolybdenum may be limited to about 2.15% to about 2.35%.

In another embodiment, by way of example only, a turbocharger kinematiccomponent is fabricated using, at least in part, an austenitic stainlesssteel alloy that includes or consists of, by weight, about 25% to about27% chromium, about 20% to about 21% nickel, about 1 to about 2%niobium, about 0.75% to about 1.7% carbon, about 3.5% to about 4.0%silicon, about 2% to about 3% tungsten, about 1.5% to about 2.5% copper,about 2% to about 2.5% molybdenum, and a balance of iron, and otherinevitable/unavoidable impurities that are present in trace amounts.Sulfur is excluded from the alloy beyond impurity levels.

With regard to the foregoing turbocharger kinematic componentembodiments, and in particular to the austenitic stainless steel alloyused to fabricate the same: the amount of chromium may be limited toabout 25.5% to about 26.5%; alternatively or additionally, the amount ofnickel may be limited to about 20.25% to about 20.75%; alternatively oradditionally, the amount of niobium may be limited to about 1.25% toabout 1.75%; alternatively or additionally, the amount of carbon may belimited to about 1.3% to about 1.7%; alternatively or additionally, theamount of silicon may be limited to about 3.6% to about 4.0%;alternatively or additionally, the amount of tungsten may be limited toabout 2.25% to about 2.75%; alternatively or additionally, the amount ofcopper may be limited to about 1.75% to about 2.25%; and, alternativelyor additionally, the amount of molybdenum may be limited to about 2.15%to about 2.35%.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive subject matter will hereinafter be described inconjunction with the following drawing figures, wherein like numeralsdenote like elements, and wherein:

FIG. 1 is a system view of an embodiment of a turbocharged internalcombustion engine in accordance with the present disclosure;

FIG. 2 is a cross-section view of the turbocharged internal combustionengine of FIG. 1 ;

FIG. 3 is a system view of a turbocharger including a waste-gate systemin accordance with the present disclosure; and

FIGS. 4A-C are photomicrographs at various magnifications illustratingthe microstructure of a ring formed of a stainless steel alloy with arelatively high silicon content in accordance with embodiments of thepresent disclosure.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and isnot intended to limit the invention or the application and uses of theinvention. As used herein, the word “exemplary” means “serving as anexample, instance, or illustration.” Thus, any embodiment describedherein as “exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments. All of the embodiments describedherein are exemplary embodiments provided to enable persons skilled inthe art to make or use the invention and not to limit the scope of theinvention which is defined by the claims. Furthermore, there is nointention to be bound by any expressed or implied theory presented inthe preceding technical field, background, brief summary, or thefollowing detailed description.

Unless specifically stated or obvious from context, as used herein, theterm “about” is understood as within a range of normal tolerance in theart, for example within 2 standard deviations of the mean. “About” canbe understood as within 10%, 5%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of thestated value. “About” can alternatively be understood as implying theexact value stated. Unless otherwise clear from the context, allnumerical values provided herein are modified by the term “about.”

All of the austenitic stainless steel alloys described herein may beunderstood as either: (1) “comprising” the listed elements in theirvarious percentages, in an open-ended context or (2) “consisting of” thelisted elements in their various percentages, in a closed-ended context.Alternatively, the austenitic stainless steel alloys described hereinmay be understood as (3) “consisting essentially of” the listed elementsin their various percentages, wherein other elements may be present inamounts not effecting the novel/nonobvious characteristics of the alloy.Thus, as used herein, the terms “comprising,” “consisting of,” and“consisting essentially of” should be understood as applicable to all ofthe ranges of alloy compositions disclosed herein.

All of the embodiments and implementations of the austenitic stainlesssteel alloys, turbocharger kinematic components, and methods for themanufacture thereof described herein are exemplary embodiments providedto enable persons skilled in the art to make or use the invention andnot to limit the scope of the invention, which is defined by the claims.Of course, the described embodiments should not be considered limited tosuch components, but may be considered applicable to any articles ofmanufacture where an iron alloy, or a stainless steel alloy may beemployed. Furthermore, there is no intention to be bound by anyexpressed or implied theory presented in the preceding technical field,background, brief summary, or the following detailed description.

As noted above, the present disclosure is directed to austeniticstainless steel alloys for use in kinematic components of a turbocharger(for use in various vehicles and other applications) for purposes forwear with regard to the use and implementation of such kinematiccomponents. As further noted above, a variable geometry turbocharger(among other possible turbocharger systems) may employ such kinematiccomponents. Accordingly, for completeness of description, FIG. 1illustrates a portion of a variable geometry turbocharger (VGT) 10comprising a turbine housing 12 having a standard inlet 14 for receivingan exhaust gas stream, and an outlet 16 for directing exhaust gas to theexhaust system of the engine. A volute is connected to the exhaust inletand an integral outer nozzle wall is incorporated in the turbine housingcasting adjacent the volute. A turbine wheel 17 and shaft assembly 18 iscarried within the turbine housing 12. Exhaust gas, or other high energygas supplying the turbocharger, enters the turbine housing through theinlet 14 and is distributed through the volute in the turbine housingfor substantially radial delivery to the turbine wheel through acircumferential nozzle entry 20.

Multiple vanes 22 are mounted to a nozzle wall 24 machined into theturbine housing using shafts 26 that project perpendicularly outwardlyfrom the vanes. The shafts 26 are rotationally engaged within respectiveopenings 28 in the nozzle wall. The vanes each include actuation tabs 30that project from a side opposite the shafts and that are engaged byrespective slots 32 in a unison ring 34, which acts as a second nozzlewall. The tabs 30, slots 32, and other described components moverelative to one another, and as such it would be desirable to reduce thefriction therebetween for tribological purposes.

FIG. 2 illustrates the general movement pattern of conventional vanes36, as used in the VGT described and illustrated above, when actuated bythe unison ring 34. Each vane tab 42 is disposed within a respectiveelongated slot 38 of a unison ring 40. In a closed position “A”, thevane tab 42 is positioned adjacent a first end 44 of the slot 38. Thisposition is referred to as a closed position because the vane is notflared radially outward, thereby serving to limit the flow of exhaustgas to the turbine. At an intermediate position “B” the unison ring 40has been rotated a sufficient amount such that the vane tab 42 is movedwithin the slot 38 away from the first slot end 44 (as opposed to secondslot end 46) towards a middle position of the slot. Again, it would bedesirable to reduce friction as the components of the vanes 36 moverelative to the components of the unison ring 40, for tribologicalpurposes.

Additionally, as noted above, waste-gate systems may also includetribological components, and as such, for completeness of disclosure,FIG. 3 illustrates an exemplary waste-gate system. Specifically, FIG. 3shows a cutaway view of an example of an assembly 300 that includes aturbine housing component 320 and a waste-gate 380. In the assembly 300,the turbine housing component 320 includes an opening 340, for example,as defined by a surface 332 of a substantially cylindrical wall portion330 of the turbine housing component 320. As shown, the wall 332 extendsto an edge (e.g., defining the opening 340) and then flattens joining arelatively flat surface 334, which may be referred to as a waste-gateseat. In the example of FIG. 3 , the surface 332 defines a relativelyshort passage, for example, having an axis (e.g., a z-axis), from whichthe surface 332 is disposed at a radial distance (e.g., an r-axis).Extending away from the opening 340, the seat 334 descends along anothersurface 336 (e.g., of the substantially cylindrical wall portion 330) toa floor 348 of an exhaust chamber formed in part by the turbine housingcomponent 320, for example, in combination with a wall surface 346. Asshown in FIG. 3 , the wall surface 346 of the turbine housing component320 rises to an edge that defines an opening 349 of the exhaust chamberand then extends outwardly to a relatively flat surface 328, which mayinclude one or more apertures, etc., such as an aperture 325, forexample, to attachment of another component to the turbine housingcomponent 320.

In the example of FIG. 3 , the waste-gate 380 includes a plug portion382 that is connected to a waste-gate arm 390. The plug portion 382includes a lower surface 381, a stem 383 that extends upwardly to anupper end 385 of the plug portion 382 and a rim surface 384 (e.g.,disposed at a radius about the stem 383 and having an axial height). Asshown, the stem 383 is received by a bore 393 of the waste-gate arm 390where the bore 393 extends between a lower surface 391 and an uppersurface 395 of the waste-gate arm 390. In the example of FIG. 3 , aclamping washer 387 clamps to the stem 383 of the plug portion 382 tothereby prevent the stem 383 from sliding through the bore 393 of thewaste-gate arm 390. Accordingly, as the waste-gate arm 390 pivots, thelower surface 381 of the plug portion 382 is positioned with respect tothe seat 334 of the turbine housing component 320 for opening andclosing of the waste-gate 380.

Typical embodiments of the present disclosure reside in a motor vehicleequipped with a gasoline or diesel powered internal combustion engineand a turbocharger. The turbocharger is equipped with a uniquecombination of features that may, in various embodiments, provideefficiency benefits by relatively limiting the amount of (and kineticenergy of) secondary flow in the turbine and/or compressor, as comparedto a comparable unimproved system. Stainless steel alloys for use inturbochargers may have operating temperatures up to about 1050° C. (orup to about 1100° C.), or greater. Some embodiments of the presentdisclosure are directed to stainless steel alloys that include ironalloyed with various alloying elements, as are described in greaterdetail below in weight percentages based on the total weight of thealloy. The description of particular effects with regard to theinclusion of certain weight percentages of materials, as set forthbelow, are particular to the alloy of the present disclosure, and assuch should not be understood as applying to any other alloy. Moreover,the description of particular effects with regard to the inclusion ofcertain weight percentages of materials is not intended to limit thescope or content of the present disclosure.

As such, in an embodiment, the stainless steel alloy of the presentdisclosure includes from about 25% to about 27% chromium (Cr), forexample from about 25.5% to about 26.5% Cr, such as about 25.5% to about26% Cr. It has been discovered that if Cr is added excessively, coarseprimary carbides of Cr are formed, resulting in extreme brittleness. Assuch, the content of Cr is preferably limited to a maximum of about 27%so as to maintain an appropriate volume fraction within the stainlesssteel for corrosion resistance.

In an embodiment, the stainless steel alloy of the present disclosureincludes from about 20% to about 21% nickel (Ni), for example about20.25% to about 20.75% Ni, for example about 20.4% to about 20.6% Ni. Niis an element to stabilize the austenite phase. Thus, the content of Nipreferably ranges from about 20% to about 21%.

In an embodiment, the austenitic stainless steel alloy of the presentdisclosure includes from about 1% to about 2% niobium (Nb), for exampleabout 1.25% to about 1.75% Nb, such as about 1.4% to about 1.6% Nb. Nbis known to be an element that forms carbides and a solid solutionstrengthening element.

In an embodiment, the austenitic stainless steel alloy of the presentdisclosure includes from about 2% to about 3% tungsten (W), for exampleabout 2.25% to about 2.75% W, such as about 2.4% to about 2.6% W.

In an embodiment, the austenitic stainless steel alloy of the presentdisclosure includes from about 1.5% to about 2.5% copper (Cu), forexample about 1.75% to about 2.25% Cu, such as about 1.9% to about 2.1%Cu.

In an embodiment, the stainless steel alloy of the present disclosureincludes from about 2% to about 2.5% molybdenum (Mo), such as about2.15% to about 2.35% Mo, for example about 2.2% to about 2.3% Mo. If thecontent of Mo is excessive, Mo is likely to form the sigma phase when itis annealed, thereby deteriorating the corrosion resistance and impactresistance, which is deleterious to the tribological properties of thekinematic components of a turbocharger described herein.

In an embodiment, the stainless steel alloy of the present disclosureincludes from about 0.75% to about 1.7% carbon (C), such as about 1.3%to about 1.7% C, for example about 1.4% to about 1.6% C. A specificembodiment may employ about 1.5% C. C has a function of improving thesintering ability of the alloy. C, when present in the relatively-highdisclosed range, also forms a eutectic carbide with niobium, whichimproves wear resistance. To exhibit such functions effectively, theamount of C is increased to about 1.3% or more. Further, C is effectivefor strengthening a material by solid solution strengthening. Tomaximize the corrosion resistance, the content of C is lowered to about1.7% and below.

In an embodiment, the stainless steel alloy of the present disclosureincludes from about 3.5% to about 4.0% silicon (Si), such as about 3.6%to about 4.0% Si, for example about 3.65% to about 3.9% Si. In anexemplary embodiment, Si is present in the stainless steel alloy of thepresent disclosure in an amount of at least 3.5%, 3.55%, 3.6%, 3.65%,3.7%, 3.75%, 3.8%, 3.85%, or 3.9%, and independently, of not more thanabout 4.0%, 3.95%, 3.9%, 3.85%, 3.8%, 3.75%, 3.7%, 3.65% or 3.6%. Aspecific embodiment may employ about 3.6% Si. Si has effects ofincreasing the stability of the alloy metal structure and its oxidationresistance. Further, Si has functions as a deoxidizer and also iseffective for improving castability and reducing pin holes in theresulting sintered products, when present in an amount greater thanabout 3.5%. If the content of Si is excessive, Si deteriorates themechanical property such as impact toughness of stainless steel.Therefore, the content of Si is preferably limited to about 4.0% andbelow.

Certain inevitable/unavoidable impurities may also be present in thestainless steel alloy of the present disclosure, for example asdescribed below with regard to phosphorous and sulfur (the amounts ofsuch described impurities (and others) are minimized as much aspractical).

In an embodiment, phosphorus (P) may be present in the alloy, but isminimized to about 0.04% or less. P is seeded in the grain boundary oran interface, and is likely to deteriorate the corrosion resistance andtoughness. Therefore, the content of P is lowered as low as possible.Preferably, the upper limit content of P is limited to 0.04% inconsideration of the efficiency of a refining process. The contents ofharmful impurities, such as P are as small as possible. However, due tocost concerns associated with removal of these impurities, and the Pcontent is limited to 0.04%.

In an embodiment, sulfur (S) may be present in the alloy, but isminimized to about 0.01% or less. S in steels deteriorates hotworkability and can form sulfide inclusions that influence pittingcorrosion resistance negatively. It should therefore be limited to lessthan 0.01%. S deteriorates the hot formability, thereby deterioratingthe corrosion resistance. Therefore, the content of S is lowered as lowas possible. The contents of harmful impurities, such as S (sulfur), areas small as possible. However, due to cost concerns associated withremoval of these impurities, the S content is limited to about 0.01%.

In some embodiments, high-cost elements that have in the prior art beenproposed for inclusion in stainless steels are specifically excludedfrom the alloy (except in unavoidable impurity amounts). Theseexcludable elements are, for example, Co, and/or V. Other excludableelements (except in unavoidable impurity amounts) are, for example, Mn,N, Ta, Al, B, La, and/or Zr.

The disclosed alloys, being stainless steel alloys, also include abalance of iron (Fe). As used herein, the term “balance” refers to theamount remain to achieve 100% of a total alloy, in terms of weight. Itshould be appreciated that this amount may differ if an embodiment“comprises,” “consists of,” or “consists essentially of” the statedelements, with the balance being Fe.

The articles of manufacture described herein, such as the kinematiccomponents of a turbocharger fabricated with the above-describedstainless steel alloys, may be formed using sintering processes, castingprocesses, or metal injection molding (MIM) processes. Further, theformed part may be subsequently machined to final dimensionalrequirements. For example, as is known in the art, sintering refers to aprocess of compacting and forming a solid mass of material by heatand/or pressure without melting the material to the point ofliquefaction. The sintered part may then be fine machined to meet finaldimensional requirements. Non-limiting examples of kinematic componentsof a turbocharger fabricated with the above-described stainless steelalloys includes nozzle rings, bushings, for example waste-gate (WG)bushings, and/or the like.

Illustrative Example

The present disclosure is now illustrated by the following non-limitingexample. It should be noted that various changes and modifications canbe applied to the following example and processes without departing fromthe scope of this invention, which is defined in the appended claims.Therefore, it should be noted that the following example should beinterpreted as illustrative only and not limiting in any sense.

Referring below to Table 1, an example metal alloy (referred to hereinas “GT-29”) was prepared with the approximate wt.-% formula: 0.75%-0.79%C, 3.66%-3.72% Si, 1.17%-1.38% Mn, 0.028%-0.041% S0.014%-0.015% P,25.81%-25.15% Cr, 20.15%-20.28% Ni, 2.15%-2.16% Mo, 1.42%-1.44% Nb,1.84%-1.88% Cu, 2.05%-2.14% W, balance Fe. The metal alloy GT-29 wasformed into several tubes (“Cast Tube 1” via casting) and plate-shapedring articles (“Ring 1” via rough casting and machining).

TABLE 1 Element C Si Mn S P Cr Ni Mo Nb Cu W Ring 1 0.75 3.66 1.38 0.0410.014 24.81 20.15 2.16 1.44 1.84 2.14 Cast Tube 1 0.79 3.72 1.17 0.0280.015 25.15 20.28 2.15 1.42 1.88 2.05  0.70-  3.50-  0.50-  25.00- 20.00-  2.00-  1.00-  1.50-  2.00- 0.10 4.50 1.50 27.00 21.00 2.50 2.002.50 3.00

Referring to FIGS. 4A-C, photomicrographs at various magnificationsillustrating the microstructure of the Ring 1 formed of GT-29 areprovided. As illustrated, the microstructure of the Ring 1 includes orconsists of chromium rich carbides embedded in a ferritic matrix.

Tubes (e.g., pins) and rings (e.g., plates) were also formed from HK 30alloy and Stainless Steel (“SS”) 310 alloy, respectively. Various alloycombinations of tubes and rings were subjected to wear-resistancetesting at various elevated temperatures. The alloys combinationsincluded: HK 30 tube/SS 310 ring, HK 30 tube/GT-29 ring, and GT-29tube/GT-29 ring. The elevated temperatures included: 300° C., 700° C.,and 850° C. The wear resistance testing was performed as follows: Thetest was a dry-sliding, reciprocating, high-temperature wear test thatinvolved determining wear between one pin and two plates.

The observed wear levels for the respective tube and ring, for eachalloy and temperature combination, are shown below in Tables 2-4. As canbe seen, tests using the Example alloy demonstrated reduced wear andreduced friction, across the temperatures tested, as compared to thetests that did not use the Example alloy. In particular, after testing,wear volume is evaluated and compared with the baseline and the wearimprovement against the baseline are shown in percent, which aredetermined based on wear volume.

TABLE 2 Improvement Materials (300° C., %) HK 30/TMC-29(GT 29) 121.4957/TMC-29(GT 29)  3 HK 30/SS 310  0

TABLE 3 Improvement Materials (700° C., %) HK 30/TMC-29(GT 29) 931.4957/TMC-29(GT 29) 92 HK 30/SS 310  0

TABLE 4 Improvement Materials (850° C., %) HK 30/TMC-29(GT 29) 761.4957/TMC-29(GT 29) 61 HK 30/SS 310  0

As such, embodiments of the present disclosure provide materials thatare suitable for use in fabricating kinematic components for turbineengines that can resist wear during elevated temperature operations. Asnoted above, examples of turbocharger systems that may include kinematiccomponents include waste-gate systems and variable geometry systems. Ofcourse, the described embodiments should not be considered limited tosuch components, but may be considered applicable to any articles ofmanufacture where an iron alloy, or a stainless steel alloy may beemployed. The described material may provide an effective, and low cost,substitute for 310-grade stainless steel or other stainless steels thathave higher nickel content or include high-cost elements.

While at least one exemplary embodiment has been presented in theforegoing detailed description of the inventive subject matter, itshould be appreciated that a vast number of variations exist. It shouldalso be appreciated that the exemplary embodiment or exemplaryembodiments are only examples, and are not intended to limit the scope,applicability, or configuration of the inventive subject matter in anyway. Rather, the foregoing detailed description will provide thoseskilled in the art with a convenient road map for implementing anexemplary embodiment of the inventive subject matter. It beingunderstood that various changes may be made in the function andarrangement of elements described in an exemplary embodiment withoutdeparting from the scope of the inventive subject matter as set forth inthe appended claims.

1. An austenitic stainless steel alloy, comprising, by weight: about 25%to about 27% chromium, about 20% to about 21% nickel, about 1 to about2% niobium, about 0.75% to about 1.7% carbon, about 3.5% to about 4.0%silicon, about 2% to about 3% tungsten, about 1.5% to about 2.5% copper,about 2% to about 2.5% molybdenum, and a balance of iron, and otherinevitable/unavoidable impurities that are present in trace amounts,wherein sulfur is excluded from the alloy beyond impurity levels, andwherein phosphorus, if present in the austenitic stainless steel alloy,is in an amount of 0.04% or less by weight.
 2. The austenitic stainlesssteel alloy of claim 1, comprising about 25.5% to about 26.5% chromium.3. The austenitic stainless steel alloy of claim 1, comprising about20.25% to about 20.75% nickel.
 4. The austenitic stainless steel alloyof claim 1, comprising about 1.25% to about 1.75% niobium.
 5. Theaustenitic stainless steel alloy of claim 1, comprising about 1.3% toabout 1.7% carbon.
 6. The austenitic stainless steel alloy of claim 1,comprising about 3.6% to about 4.0% silicon.
 7. The austenitic stainlesssteel alloy of claim 1, comprising about 2.25% to about 2.75% tungsten.8. The austenitic stainless steel alloy of claim 1, comprising about1.75% to about 2.25% copper.
 9. The austenitic stainless steel alloy ofclaim 1, comprising about 2.15% to about 2.35% molybdenum.
 10. Aturbocharger kinematic component comprising, at least as a part of itsconstituency: an austenitic stainless steel alloy, wherein theaustenitic stainless steel alloy comprises, by weight: about 25% toabout 27% chromium, about 20% to about 21% nickel, about 1 to about 2%niobium, about 0.75% to about 1.7% carbon, about 3.5% to about 4.0%silicon, about 2% to about 3% tungsten, about 1.5% to about 2.5% copper,about 2% to about 2.5% molybdenum, and a balance of iron, and otherinevitable/unavoidable impurities that are present in trace amounts,wherein sulfur is excluded from the alloy beyond impurity levels, andwherein phosphorus, if present in the austenitic stainless steel alloy,is in an amount of 0.04% or less by weight.
 11. The turbochargerkinematic component of claim 10, wherein the austenitic stainless steelalloy comprises about 25.5% to about 26.5% chromium.
 12. Theturbocharger kinematic component of claim 10, wherein the austeniticstainless steel alloy comprises about 20.25% to about 20.75% nickel. 13.The turbocharger kinematic component of claim 10, wherein the austeniticstainless steel alloy comprises about 1.25% to about 1.75% niobium. 14.The turbocharger kinematic component of claim 10, wherein the austeniticstainless steel alloy comprises about 1.3% to about 1.7% carbon.
 15. Theturbocharger kinematic component of claim 10, wherein the austeniticstainless steel alloy comprises about 3.6% to about 4.0% silicon. 16.The turbocharger kinematic component of claim 10, wherein the austeniticstainless steel alloy comprises about 2.25% to about 2.75% tungsten. 17.The turbocharger kinematic component of claim 10, wherein the austeniticstainless steel alloy comprises about 1.75% to about 2.25% copper. 18.The turbocharger kinematic component of claim 10, wherein the austeniticstainless steel alloy comprises about 2.15% to about 2.35% molybdenum.19. A turbocharger comprising the turbocharger kinematic component ofclaim
 10. 20. A vehicle comprising the turbocharger of claim 19.